Topic 10 - Genetics


The Sciences: Chapter 23 and 24


1) What is the connection between a gene and a chromosome?


Answer: Genes are small lengths of DNA molecule that makes up a chromosome. So, a gene is part of a chromosome. Both genes and chromosomes are made up of DNA, but chromosomes also have protein associated with it.


2) If you crossed two gray cats and they had two gray kittens and five black kittens, could you conclude that black was dominant?


Answer: No, because if black were dominant one or both of the parent would have to be black. If black were dominant then the black kittens would have to be BB or Bb. This means at least one parent (more likely both) had to have one dominant allele B to have any black kittens. Since neither of the parents is black this can not be possible.


If Black was dominant

Gametes from black parent (genotype Bb)



Gametes from other parent


Bb (black)



Bb (black)



In this case, the two gray cats are heterozygous and by chance, the two recessive alleles for black got together in five of the seven fertilizations which produced the seven kittens.


If Black is recessive

Gametes from gray heterozygous parent (genotype Bb)



Gametes from gray heterozygous parent

(genotype Bb)



Bb (gray)


Bb (gray)

bb (black)



3) Given what you know about the effect of ultraviolet light on DNA, why should you wear sunscreen when you are outdoors?


Answer: UV light harms cells in the epidermis (the skin's outermost layer), by having the blood vessels in the skin's deeper layers dilate and turn the skin red (sunburn). With regular sun exposure, the cells will produce more pigment called melanin as a way to absorb UV rays. As the pigment level increases the color of the skin darkens and a tan develops. People with dark skin color already have more pigment and so do not develop a tan and don't burn as readily. The pigment in your skin, melanin, doesn't absorb all the UV rays and some of the rays may injure the DNA in the living cells. Sunscreen acts as a filter that absorbs additional UV rays and dissipates their energy. The evidence today shows that sunscreens primarily filter the shorter UV rays (UVB) and that UVA rays are responsible for increased skin aging. The best protection from the sun is to stay out of it or wear clothes that cover the majority of your skin, but a sunscreen is a better alternative than nothing or tanning oil.



Q1=They both carry genetic information.

Q2=that black is the dominate gene.

if you have 2 gray cats, B g


g gB gg

The B represents the black gene and the g represents the gray gene. This modle shows that if the black is the dominate gene. 3 of the 4 offspring should be black.

Q3=The uv rays can cause mutation in DNA causing harmful effects such as skin cancer.


1. Well both genes and chromosomes are in the long strand of DNA. The chromosomes contain all or most of the genetic information of a cell. The gene is the acutal characteristic that we inherit. So both make up DNA.

2. Yes black would be dominant because it is a 3:1 ratio. It is found by exploring the possible genetic combinations. That would have be my answer

3. Ultra violet rays along with other chemicals such as nuclear radiation and x rays are all things that cause oxidation reactions in cells. So this can cause an alteration in the genes and cause a mutation. We all are mutants! But protectings from the UV rays with sunscreen is a good idea.


1. The connection between a gene and a chromosome is that a gene is on a chromosome. Also the gene and the chromosome both carry DNA.

2. Yes because there were more black cats than gray cats. Maybe the mom and the dad both carried a black color trait and over took the gray trait.

3. You wear sunscreen when you are outside because the ultraviolet rays can cause cancer. If you get too much of it than it can change some of your DNA which will be mutant DNA which can cause cancer cell which can eventually kill you if you don't catch it in time to get medicine.


Q1=Both are a section of DNA. A gene carries the information needed to assemble one protein. A chromosome is wrapped around a series of protein.

Q2=Yes, the cats were able to have gray kittens because they had two recessive genes to be gray themselves. They had more black kittens than gray kittens even though both of the parents were gray. This means that black is the dominant trait and gray is the recessive trait.

Q3=Ultraviolet light is absorbed by your body's cells and can cause extensive damage to your DNA. We use sunscreen to prevent sunburn and skin cancer.


1. A gene is smaller than a chromosome. There are many genes in a chromosome. A gene is one section of long molecule of DNA carrying information needed to assemble one protein, and a chromosome is a long strand of the DNA double helix that is wrapped around a series of protein cores.

2. No, if black was a dominant trait then the two gray cats that produced the kittens would have to be black. Each parent cat would be Dd.

3. Ultraviolet light produces oxidizing chemicals as well as causes oxidation reactions in cells. The test explains that mutations in offspring can develop if the DNA of a parent's egg or sperm is altered. Mutation is good to an extent because it makes everyone a unique person but also can be bad if certain mutations are developed. "Staying away" from agents such as certain chemicals, nuclear radiation, x-rays, and ultraviolet light will decrease your chance of passing on an undesired mutation to offspring. Sunscreen helps block UV light.


Q1=Genes are a part of a molecule in DNA. Then, DNA in eukaryotes is found in the cell nucleus which is in a chromosome.

Q2=It's simple to conclude that black was the dominant trait because the five black kittens could have recieved black dominant genes from their parents. however, the 'parent' cats were gray meaning they could have recieved gray recessive genes from their parents.

Q3=Ultraviolet lights causes a "mismatch' in DNA and then goes into mismatch repair which can creat defects. These things could turn into cancer.


Q1=Genes and chromosomes are linked because the gene is found within the DNA of a chromosome. A gene is a part of a long molecule of DNA. DNA is contained in the eukaryotic cells nucleus in the structure of the chromosome.

Q2=Yes because the 2 grey cats had more black kittens than grey kittens. This could be because in the adult cats they had a dominent trait of grey and a recesive trait of black. When the kittens were concieved the cats passed on their recesive trait to be the kittens dominent trait and 5 of the seven kittens were born black.

Q3=Ultraviolet light causes a mismatch in the cells DNA. This in turn causes the mismatch repair to go into effect. Althought the cell can be repaired most of the time there can still be defects that occur and the problem may not always be fixed. This could cause cancer.


Q1=The gene is on the chormosone and gives the choromone the information that it needs.

Q2=Yes the black would be considered the dominant gene, where the gray would be considered the resesive gene.

Q3=Because our bodies make up do not allow us to be able to handle the ultaviolet light, so we need to apply a coating of sunscreen to protect our skin.


Q1=The gene is known as the unit of inheritance. It is in the form of a long molecule of DNA. A chromosome is a DNA molecule that contains all of most of the genetic info. of a cell. So genes are found inside a chromosome.

Q2=Well, I really don't have clue one to this one. I guess you could make an argument to either side of the answer. Yes it is dominant because the two gray kittens and the parents could be the dominant and for some reason the black, which is recessive, showed. Or, you could argue that the gray was recessive in the kittens and parents and the black was dominant and it showed.

Q3=The effect of UV rays are called mutations. It causes damages in the nature of the DNA. It can cause cancer for example.


1. A chromosome is related to a gene because it contains a genetic element that carries genes that are necessary for a cell to function.

2. I would say that black was the dominant trait for the black kittens. When a dominant and recessive gene are together the dominant gene is preferred over the recessive gene. Black is more dominant over gray, as gray would be over white.

3. You should wear sunscreen because UV light can kill cells and cause negative effects on DNA. Sunscreen will protect the skin from mutations of the cells, which can lead to cancer and other harmful effects such as premature aging.


Q1=they are both long strands of sure there are more, but this is all i could find!

Q2=you can conclude that black was the dominant trait because the gray was recessive, it was there, but it was not expressed, it can however be passed along to other generations. in this case, the black would have been dominant, but the grey, the recessive, was passed along to some kittens while the black was passed along to most of the kittens.

Q3=UV light, and other chemicals cause oxidation in cells. this will alter the sperm or egg and intern alter the offspring. mutations, for example are one thing that can happen. fortunatly this does not happen too often because the body has developed a repair mechinism that will take care of almost all damage as soon as it happens.


1. They are both part of a DNA strand in a double helix. A chromosome is a long strand of the DNA double helix, with the strand wrapped around a series of protein cores. A gene is a section of a long strand of DNA, which as I already said, is the chromosome.

2. No, I would not conclude that black was the dominant trait. Each kitten inherited a trait from each parent. The father could've had gray as a dominant trait and the mother could've had black as her dominant trait. That doesn't mean that all of her kittens will be black. Some kittens inherited her dominant trait as their dominant trait and others inherited their fathers, or vice versa.

3. If you have a family history of cancer, being exposed to ultraviolet rays could increase your chance of getting skin cancer. If you already have a high risk of cancer, exposing yourself to this light would definitely add to your risk; wearing sun screen can decrease your chance of getting skin cancer.


Q1=A chromosome is a long strand of DNA double helix, with the helix wrapped around a series of protein cores. A unit of biological inheritance, or a section of long molecule of DNA. One gene carries the information needed to assemble one protein. Proteins make up a strand of DNA, and genes are required to make a protein. They are all tied together. A gene contains the traits that are carried in a persons DNA. One gene equals one protein equals one chromosome equals a strand of DNA.

Q2=Not necessarily. Gray kittens could be dominant, because both parents are gray, apparently with one or both being recessive black or carrying a black gene. The kittens could have a black gene showing but carry a gray trait also. It could just be that the black trait is showing itself. Otherwise, it is difficult to determine the correct recessive/dominant genes due to the fact that on Mendel's chart, there are either four or sixteen examples used for a trait. There would need to be more information given to figure the correct dominant trait out.

Q3=Chemical analysis indicates that human DNA is damaged on a daily rate of 10,000 hits per cell. The body has mechanisms to combat this, so most of the damage is repaired immediately. Sunscreen is a way to slxow the rate of damage sustained on a human's system, especially the skin, and the higher the spf, the higher the rate of slowing the damaging effects. Sustained damage can result in mutations, which can show themselves in different ways. They can show themselves in a "sun burn", wrinkles in the skin or they can show themselves in the form of melanomas, the most severe being malignant melanoma, or skin cancer. That is why it is important to wear sunscreen if you are out for increased amounts of time, to protect your skin from the dangerous effects of "mutation".